Abstract 13289: Reduction in Extracellular Volume Fraction After Mitral Valve Repair of Chronic Mitral Regurgitation: A Cardiac MRI Pilot Study
Bibliographic record
Abstract
Background: Global extracellular volume fraction (ECV) assessed with cardiac magnetic resonance (CMR) has been shown to be elevated in patients with chronic mitral regurgitation compared with healthy controls. Limited work has been published on ECV changes following reduction in chronic volume overload with mitral valve intervention. We examined changes in ECV in patients with chronic mitral valve regurgitation after surgical mitral valve repair (SMVR). Methods: All patients underwent CMR studies before and after SMVR. CMR studies were performed with cine, phase contrast, T1 maps, and late gadolinium enhancement (LGE) imaging. Mid, short axis T1 maps were divided into 6 cardiac segments, each classified as LGE absent or present. ECV was derived from T1 maps using area-weighted averages of only segments where LGE was absent, by a reader blinded to study date, clinical history and valve status. Results: Fifteen patients underwent SMVR a median of 1.4 (interquartile range [IQR] 0.8, 2.3) months after an initial CMR study (Table). Repeat CMR was performed a median 12.4 (IQR 7.2, 19.2) months after SMVR. None were on calcium channel blockers, nitrates, or direct arterial vasodilators. Following SMVR, significant reverse remodeling was seen with reductions in indexed left atrial volume and left ventricular parameters except end systolic volume (Table). ECV decreased from a mean 28.3% to 26.0% (p=0.01) (Table). No significant correlation was seen between changes in left sided CMR parameters and ECV (p=NS). Conclusion: In this pilot study of patients with significant chronic mitral regurgitation undergoing valve repair, a reduction in extracellular volume fraction was seen after 6 months or more, suggesting a decrease in myocardial fibrosis alongside reverse structural remodeling. Larger studies are needed to substantiate these findings and evaluate the clinical significance of ECV changes beyond cardiac reverse remodeling in patients undergoing mitral valve repair.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".